<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
  <style>
    .father{
      width: 500px;
      height: 350px;
      background-color: red;
      margin: 0 auto ;
      /*记住这一句即可*/
      overflow: hidden;
    }
    .son{
      width: 100px;
      height: 80px;
      background-color: aqua;
      margin-top: 200px;

    }
  </style>
</head>
<body>
<div class="father">
  <div class="son"></div>
</div>
</body>
</html>